Background. Since 2016, there have been multiple treatment advancements for spinal muscular atrophy (SMA). These FDA-approved disease modifying therapies (DMTs) have changed population outcomes and have led to increased community interest on the safety and efficacy of combination therapy.
Objectives. Since 2017, Cure SMA has hosted an annual Community Update Survey (CUS) to better understand the demographics and treatment experiences of those with SMA. The survey is completed by adults with SMA and caregivers of affected individuals. The purpose of this analysis is to present rationale for more than one DMT use as obtained from the 2023 CUS.
Results. Responses were fielded from April 20-July 5, 2023. Respondents indicated reasons for multiple therapy use if more than one DMT was used. For the purpose of this analysis, definitions for combination and sequential therapy were created. Combination therapy was receiving more than one DMT at the same time and includes adding a therapy after gene replacement therapy (GRT). Sequential therapy was receiving more than one DMT at different time points and includes GRT given after discontinuing other DMTs. Reasons for multiple therapy use were not exclusive.
699 surveys were completed for 688 unique individuals. The final sample size included 215 children and 222 adults with SMA. Non-U.S. residents (n=47), those with missing treatment information (n=197) and birthdates (n=1), and duplicate surveys (n=17) were excluded. 187 surveys were completed by adults with SMA and 250 surveys were completed by caregivers.
113 (52.6%) children, and 141 (63.5%) adults were treated with single therapy. 54 (25.1%) children and 78 (35.1%) adults were treated sequentially, and 48 (22.3%) children and 3 (1.4%) adults were treated with combination therapy. Reasons for sequential treatment include wanting a different DMT (72.6% for children; 88.0% for adults), physician recommendation (40.8% for children; 17.8% for adults), wanting all possible DMTs (39.6% for children; 33.8% for adults), and loss of function (12.0% for children; 27.3% for adults). Reasons for combo treatment for children were wanting a different DMT (40.5%), physician recommendation (78.7%), wanting all possible DMTs (82.2%), and loss of function (14.0%). Reasons for combo treatment among adults was not reported due to small sample size.
Conclusions. These results help to identify rationale for pursing multiple therapies to help inform future treatment regimens.